shell: silencing and disowning commands added

wiki/linux/shell.md

@@ -15,3 +15,27 @@ dash.
 - `sudo ln -sfT /bin/dash /bin/sh` - link /bin/sh to dash
 - `sudo vim /usr/share/libalpm/hooks/bash-update.hook` - setup a hook to avoid
 bash resetting the symlink
+
+## Disown a Command
+
+This section is based on a guide by
+[baeldung](https://www.baeldung.com/linux/detach-process-from-terminal).
+Disowning a command removes it from the current shell.
+Commands that are detached from a shell will not terminate upon its closure.
+A command can be disowned simply by appending `& disown` at the end of it.
+It will then provide the PID of the command that got disowned.
+
+## Silencing a Command
+
+This section is based on a guide by
+[baeldung](https://www.baeldung.com/linux/silencing-bash-output).
+If the output of a command is unwanted it can be silenced.
+There are two parts that can be silenced independently.
+Non-error outputs (stdout) can be silenced by appending `1> /dev/null` to the
+command.
+Due to the `1` being ommitable `> /dev/null` has the same effect.
+Error outputs (stderr) can be silenced by appending `2> /dev/null`.
+The complete output of both stderr and stdout can be silenced by appending
+`> /dev/null 2>&1` to the command.
+A shortened version of it not possible on all shells is `&> /dev/null`.
+